"I can't say for certain it was al Qaeda yet, but I wouldn't be surprised if it was," Bush told reporters as he toured tornado damage in this small Missouri town.

"There's a lot of suspicion it is al Qaeda. Al Qaeda is a group of people that they don't care about taking innocent life, and obviously these killers didn't care about innocent life," he said.

Simultaneous car bombings late Monday ripped into three residential compounds housing Americans and other Westerners, killing 20 people, including eight Americans, and wounding nearly 200 other people. Nine terrorists also were believed to have perished in the attacks.

Bush said officials would assess all threats and take the necessary precautions for Americans' safety in Saudi Arabia.

"One thing is for certain, the people that killed the Americans and other innocent life will be tracked down and brought to justice. It doesn't matter how long it takes," he said. "The war on terror goes on."

Bush said he would get a full briefing on the attacks from CIA Director George Tenet. "Let me get back to Washington and get the facts," he said.

In Washington, the Bush administration was strongly criticized by some Democrats for its handling of the war on terror. Sen. Bob Graham -- a White House hopeful -- said the Saudi bombings "could have been avoided."(Full story)

Asked about how well coordinated the attacks were, Bush said, "It was very well planned."

When a reporter suggested that would mean the terrorists were well-financed, Bush cut him short: "It doesn't take much money to put a car bomb together. It takes hatred. It takes hatred in your heart. It takes an absolute disregard for innocent life, and that's the nature of al Qaeda."

Al Qaeda is the terrorist group headed by Saudi exile Osama bin Laden that carried out the September 11, 2001, terror attacks that killed about 3,000 people.

At an earlier stop in Indianapolis, Indiana, Bush condemned the bombings, calling them "ruthless murder."

"These despicable acts were committed by killers whose only faith is hate, and the United States will find the killers and they will learn the meaning of American justice," Bush said as he finished a tour of states to promote his tax-cut plan.

Saudi statement

The White House took welcome notice of a statement by Saudi Crown Prince Abdullah about the bombings. He lambasted those responsible for the blasts.

The statement was "the strongest thing we have ever seen from them," said a senior U.S. official involved in national security affairs, who voiced hope it was a sign the Saudis' "personal pain" would lead them to closer cooperation with the United States.

Significantly, the Saudi government shared an advance copy of the crown prince's statement with the White House. In it, the Saudi regent called those responsible for the bombings "monsters" and said the bombers would not be considered martyrs but suffer a "destiny that is harsh in hellfire."

The crown prince's statement that the attacks could not be justified under Islam or through the Quran was "a major positive" and "a very important signal from the Saudis," the official said.

The official suggested that the fact that Saudis were killed in the attacks might have something to do with tough rhetoric. "These people didn't just attack outsiders -- they shot their way through Saudis and killed Saudis as part of these acts and that appears to have added to the power of how (Saudi officials) are interpreting this," the official said.

-- Senior White House Correspondent John King contributed to this report.